M1028A3 Front Locker

[Curtisje]

I opened the front end and found what I think is a Trac-loc limited slip. It also has 586 stamped on the ring gear and etched into the pinion. I'm assuming that means my truck has 5.86 gears instead of the standard 4.56 most CUCV's come with. Can anyone confirm this?

 

[frank8003]

This is what I found.
M1028A3 is 9400lb GVW
Front axle is Dana 60
Rear axle is Dan 70

https://torqueking.com/product/sku/id-a-1977-1991-gm-dana-60-front-axle-idn-119/

View attachment dana spicer 60-70 5315-3.pdf

page three in the PDF describes how to identify the particulars of the axle.

I see them for sale with the following information

-Dana 60 front axle 4.56 gears. trac lock limited slip differential
-Dana 70 rear axle 4.56 gears. Detroit locker

 

[royalflush55]

41-9 stamped in ring gear means 41 teeth on ring gear and 9 teeth on pinion gear. 41 divided by 9 equals 4.56 ratio. 586 is probably May 1986.

 

[BradL84D30M1008]

Great pics!

 

[ridenby]

Use https://www.amazon.com/ACDelco-10-4...t_4?ie=UTF8&psc=1&refRID=B8ENNC57TECFB2GQ5ABW

 

[Curtisje]

41-9 stamped in ring gear means 41 teeth on ring gear and 9 teeth on pinion gear. 41 divided by 9 equals 4.56 ratio. 586 is probably May 1986.

The truck is a 1985 model. 586 must be for something else.

 

[royalflush55]

Might have a 1986 rearend in it!

 

[Curtisje]

Might have a 1986 rearend in it!

Anything is possible but I'm not sure what the 586 stamped into the front differential ring gear has to do with the rearend.

 

[royalflush55]

Front differrential! Front axle!

 

[ken]

Most of these trucks went through a referb at some point. Rebuilds depended on what was wrong. You can expect to find many replaced parts. Also the odometer is most likely not the true mileage. I would bet 586 would mean May of 1986. The rebuild tag on one of the diff cover bolts was most likely lost/removed many oil changes ago.

 

[Curtisje]

Most of these trucks went through a referb at some point. Rebuilds depended on what was wrong. You can expect to find many replaced parts. Also the odometer is most likely not the true mileage. I would bet 586 would mean May of 1986. The rebuild tag on one of the diff cover bolts was most likely lost/removed many oil changes ago.

The tags were there. The truck was manufactured in 10/84. The newest tire on it was manufactured in 1988. The odometer read 36,400 miles and from everything I've inspected I believe it to be accurate. Speedometer works fine as well.

The drivers side door striker bolt is worn quite a bit though.

 

[Curtisje]

After some more thought I think you guys are right about 586 being the date for the ring and pinion, probably the install date. The front diff had a LOT of sloppy rtv work by someone and I swear there were 2 gaskets. I had to use a wire wheel to remove them from both the diff housing and diff cover. The rear, however, had only the gasket, no rtv. The rear diff cover dropped into my drain pan shortly after I removed all the bolts. I didn't have to pry it at all. The gasket looked great, no cracks or missing material.

 

[royalflush55]

Ring gear and pinion were manufactured as a matched set in May 1986 and could have been installed anytime between then and now.